<template>
    <el-select :value="valueTitle" :clearable="clearable" @clear="clearHandle">
        <el-input
                class="selectInput"
                :placeholder="placeholder"
                v-model="filterText">
        </el-input>

        <el-option :value="valueTitle" :label="valueTitle" class="options">
            <el-tree
                    id="tree-option"
                    ref="selectTree"
                    show-checkbox
                    :accordion="accordion"
                    :data="options"
                    :props="props"
                    :node-key="props.value"
                    :default-expanded-keys="defaultExpandedKey"
                    :filter-node-method="filterNode"
                    @check="handleNodeClick" >
            </el-tree>
        </el-option>
    </el-select>
</template>

<script>
    export default {
        name: "el-tree-select",
        props:{

            // 配置项
            props:{
                type: Object,
                default: {
                    value:'id',             // ID字段名
                    label: 'title',         // 显示名称
                    children: 'children'    // 子级字段名
                }
            },

            // 选项列表数据(树形结构的对象数组)
            options:{ type: Array, default: [] },

            // 初始值
            value:{ type: Number, default: null },

            // 可清空选项
            clearable:{ type:Boolean, default: true },

            // 自动收起
            accordion:{ type:Boolean, default: false },
            placeholder:{
                type:String,
                default:()=>{return "检索关键字"}
            }
        },
        data() {
            return {
                filterText: '',
                valueId: this.value,
                valueTitle:'',
                defaultExpandedKey:[]
            }
        },
        mounted(){
            this.initHandle()
        },
        methods: {
            // 初始化值
            initHandle(){
                if(this.valueId){
                    this.valueTitle = this.$refs.selectTree.getNode(this.valueId).data[this.props.label]     // 初始化显示
                    this.$refs.selectTree.setCurrentKey(this.valueId)       // 设置默认选中
                    this.defaultExpandedKey = [this.valueId]      // 设置默认展开
                }
                this.initScroll()
            },

            // 初始化滚动条
            initScroll(){
                this.$nextTick(()=>{
                    let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
                    let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
                    scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
                    scrollBar.forEach(ele => ele.style.width = 0)
                })
            },

            // 切换选项
            handleNodeClick(node){
                this.$refs.selectTree.setCheckedKeys([]);
                this.$refs.selectTree.setCheckedKeys([this.props.value]);
                this.valueTitle = node[this.props.label]
                this.valueId = node[this.props.value]
                this.$emit('getValue',this.valueId)
                this.defaultExpandedKey = []
            },

            // 清除选中
            clearHandle(){
                //this.$refs.selectTree.setCheckedKeys([]);
                this.valueTitle = ''
                this.valueId = null
                this.defaultExpandedKey = []
                this.clearSelected()
                this.$emit('getValue',null)
            },

            // 清空选中样式
            clearSelected(){
                let allNode = document.querySelectorAll('#tree-option .el-tree-node')
                allNode.forEach((element)=>element.classList.remove('is-current'))
            },
            filterNode(value, data) {
                if (!value) return true;
                return data.name.indexOf(value) !== -1;
            }

        },

        watch: {
            value(){
                this.valueId = this.value
                this.initHandle()
            },
            filterText(val) {
                this.$refs.selectTree.filter(val);
            }
        },
    }
</script>

<style scoped>
    .el-scrollbar .el-scrollbar__view .el-select-dropdown__item{
        height: auto;
        max-height: 274px;
        padding: 0;
        overflow: hidden;
        overflow-y: auto;
    }
    .el-select-dropdown__item.selected{
        font-weight: normal;
    }
    ul li >>>.el-tree .el-tree-node__content{
        height:auto;
        padding: 0 20px;
    }
    .el-tree-node__label{
        font-weight: normal;
    }
    .el-tree >>>.is-current .el-tree-node__label{
        color: #409EFF;
        font-weight: 700;
    }
    .el-tree >>>.is-current .el-tree-node__children .el-tree-node__label{
        color:#606266;
        font-weight: normal;
    }
    .selectInput{
        padding: 0 5px;
        box-sizing: border-box;
    }
</style>
